(i) Field of the Invention
The present invention relates to fans of a type known as box fans.
(II) Description of the Prior Art
Fans in which the fan-blade assembly is exposed are potentially dangerous, particularly to children, consequently the enclosure of the fan blade assembly affords obvious advantages. Fan-blade assemblies have been enclosed within cage-like structures and box-like structures. The latter type usually consist of a box containing two openings in opposing faces which are joined to form a duct containing the motor and the fan-blade assembly. Both openings are normally enclosed by a grille. A particular type of box fan is disclosed in Australian Pat. No. 459,701, in which the fan blade assembly is partially located within a dished rear grille and the front grille is rotated by means of a slipping clutch cooperating with an output shaft connected to the motor through reduction gearing.
The parts comprising the box which contains the fan are, in the preferred embodiment described in specification No. 459,701, assembled by the use of screws, the heads of which are visible from the exterior of the fan. It is readily discernible how such a fan can be disassembled and it is therefore relatively easy for persons to expose themselves to possibly dangerous electrical voltages on electrical components of the fan. This is, of course, undesirable of itself and, furthermore, may lead to safety authorities requiring that the electrical motor be earthed thus necessitating the use of a three-core electrical flex for coupling the fan to an electricity supply, whereas a two-core flex may otherwise be permissible with consequent cost savings in manufacture. Again, additional cost savings may also accrue by virtue of the replacement of screws with less labour intensive means.